Cadmium iodide osmium (CdIOs) staining for acidic phospholipids on cartilage membranes, improved by cysteine soak and hexylene glycol embedding intermediate, will be further investigated with phospholipase, phospholipase inhibitors and quantitation. In the gut, specific phospholipids (fed to rats) will be coupled with this improved method to test for any phospholipid staining specificity. To confirm that zinc iodide osmium (ZnIOs) stains for R-SH or R-S-S-R groups, research will investigate effects of -SH inhibitors and electron transport chain inhibitors on staining the inner matrix of isolated mitochondria. The nature of copper iodide osmium (CuIOs) stained intramitochondrial precipitates seen only in mononuclear preosteoclasts and newly formed osteoclasts will be studied with key hormones and suspected inhibitors. Comparing ferrous iodide osmium (FeIOs) used with FeCl3 plus K3Fe(CN)6 to colloidal iron and ferric hydroxychloride will evaluate our simplified, improved technique for staining the glycoprotein halyx. Selenium iodide osmium (SeIOs) will be investigated to ascertain its peroxidase or lipase specificity. Substitution of fluoride for iodide in Zn and Cd complexes will determine whether varying halides affects stain specificity. Cation-halide osmium complexes will be tested in animal model systems of bone repair, hormonal control of adult bone metabolism and nutritional deficiency.